At scale, rare and unexpected events will happen. Things eventually will go wrong. This talk dives into what can go wrong at scale and how to architect applications to ride through disaster obliviously. We’ll talk about AWS infrastructure design including Regions and Availability Zones and show how applications can be written and operated to best exploit this industry-unique infrastructure redundancy model. Believing that experience is one of the best teachers, we will go through some of the more interesting and educational industry post mortems including some experienced at AWS to motivate these application design decisions and show how they can mitigate the damage of the truly unexpected.